FIELD: motors and pumps.
SUBSTANCE: invention can be used in valve drives for internal combustion engines. Actuator (1) for axial displacement of an object comprises actuator piston (4) and hydraulic circuit (20). Actuator piston (4) comprises actuator piston rod (7), having first end (8) and second end. Actuator piston (4) is displaceable in the axial direction in a reciprocating manner between a first position and a second position. Hydraulic circuit (20) comprises liquid filled chamber (21). First end (8) of actuator piston rod (7) is arranged to be displaced in the axial direction within said liquid filled chamber (21) in conjunction with axial displacement of actuator piston (4). Axially extending recess (22) opens in said liquid filled chamber (21) and is arranged to receive first end (8) of actuator piston rod (7) when actuator piston (4) is in said first position. Actuator piston rod (7) in the area of first end (8) presents a cylindrical envelope surface (24). Recess (22) presents cylindrical inner surface (25). Cylindrical envelope surface (24) and cylindrical inner surface (25) represent matching shapes. Actuator comprises a passage extending between recess (22) and liquid filled chamber (21) when cylindrical envelope surface (24) and cylindrical inner surface (25) are located in overlapping configuration. Section of a predetermined maximum overlap is constituted by braking overlap. Passage in said braking overlap section has a cross section area that decrease as a function of increasing overlap between cylindrical envelope surface (24) and cylindrical inner surface (25). Cross section area of the passage at the beginning of said braking overlap section decreases with decreasing derivative, and at the end of said braking overlap section decreases with increasing derivative, as a function of increasing overlap.
EFFECT: technical result is to reduce the closing speed immediately before the engine valve comes into contact with the valve seat.
13 cl, 18 dwg
